Mechanical telephone



' (No Model.) 8

N. B. S'T UBBLEFIELD & S. O. HOLGOMR, MECHANICAL TELEPHONE.

No. 378,183. Patented Feb. 21, 1888.

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mike Elem I UNITED STATES NATHAN B. STUBBLEFIELD PATENT OFFICE.

AND SAMUEL O. HOLCOMB, OF MURRAY,

KENTUCKY.

MECHANICAL TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 3'78, 183, datedFebruary 21,1888. Application filed February 19, 1887. Serial No.228,231. (No model.)

To all whom it may concern.-

Be it known that WG,NATHAN B. STUBBLE- FIELD and SAMUEL C. HoLooMB,citizens of the United States, residing at Murray, in the county ofGalloway and State of Kentucky, have invented a new and usefulImprovement in Acoustic Telephones, of which the following is aspecification.

Our invention relates to an improvement in acoustic telephones; and itconsists in the pe culiar construction and combination of devices, thatwill be more fully set forth hereinafter, and more particularly pointedout in the claims.

In the drawings, Figure l is a front elevation of an acoustic telephoneembodying our improvements. Fig. 2 is a vertical central sectional viewof the same.

A represents a base-board, which is made of wo0d,and is circular inshape and provided with a central opening, B. The face and edges of theboard are covered with velvet cloth, as at O, the said cloth having itsedges drawn over and upon the rear side of the base-board, and securedthereto by means-of a circular sheet of tin, D, the latter having itsedges secured to the base-board by means of headed nails E.

F represents a pair of screws which extend through the base-board, oneabove and the other below the central opening, B, the function of thesaid screws being to secure thetelephone to a wall or other supportingobject. From the face of the lower side of the base-board projects ahook, G, from which is suspended a mallet, H, that is used for callingthe operator at the distant station.

I represents a circular drum which is made of sheetmetahpreferably oftin. Over theouter side of the said drum is stretched a diaphragm, K,which is made of linen or other suitable cloth, and has its edge securedto the sides of the drum by means of cords L,which are wound and tiedtightly around the drum, so as to surround the edge of the diaphragm, asshown at Fig. 2. The outer side of the drum is then covered with velvetcloth, as at M. From the inner edge of the drum pro ject two or moresecuring-pins, N, which are adapted to enter corresponding openings madein the face of the base board, and whereby the drum and the diaphragmare secured centrally to the base-board. The space between thebase-board and the diaphragm and inclosed by the drum constitutes anair-chamber with which the opening B communicates.

0 represents a button, the shank of which passes through an opening madein the center of the diaphragm, the button resting against the frontside thereof. A wire,P,is attached to the shank of the said button andis drawn ti ght-ly,so as to tightly stretch the diaphragm, and extendsthrough the opening B, the other end of the said wire being attached toa similar button in the diaphragm of a companion acoustic telephonelocated at the distant station.

In order to obtain the best results, we coat the diaphragm with copalvarnish on both sides, which varnish, after it is dry, contributesmaterially to the resilience of the diaphragm and increases itssensibility, thereby enabling it to vibrate with maximum amplitude andmobility. The outer side of the diaphragm is then gilded or bronzed.

The simplicity of the telephone will commend itself to the public,whileits advantages for talking over crooked or crossed lines will be seen atonce.

Having thus described our invention, we

claimthe eye of the button, substantially as described.

In testimony that we claim the foregoing as our own we have heretoaffixed our signatures in presence of two witnesses.

NATHAN B. STUBBLEFIELD. SAMUEL C. HOLOOMB. Witnesses:

OSCAR HOLT, B. B. LINN.

